U.S. patent number 6,053,261 [Application Number 09/262,815] was granted by the patent office on 2000-04-25 for flow pulsing method and apparatus for the increase of the rate of drilling.
Invention is credited to Bruno H. Walter.
United States Patent |
6,053,261 |
Walter |
April 25, 2000 |
Flow pulsing method and apparatus for the increase of the rate of
drilling
Abstract
A simple and economical device is placed in a drill string to
provide a pulsating flow of the pressurized drilling fluid to the
jets of the drill bit to enhance chip removal and provide a
vibrating action in the drill bit itself thereby to provide a more
efficient and effective drilling operation. Operation of the device
is such that a pronounced negative pulse precedes the positive
pulse. Between pulses there is a short time delay and this feature
will further enhance drilling rates. Device automatically bypasses
all fluid if it is disabled.
Inventors: |
Walter; Bruno H. (North
Vancouver, CA) |
Family
ID: |
4158098 |
Appl.
No.: |
09/262,815 |
Filed: |
March 5, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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844446 |
Apr 18, 1997 |
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Foreign Application Priority Data
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Apr 29, 1996 [CA] |
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2175296 |
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Current U.S.
Class: |
175/234;
175/243 |
Current CPC
Class: |
E21B
4/14 (20130101); E21B 7/18 (20130101) |
Current International
Class: |
E21B
21/00 (20060101); E21B 21/10 (20060101); E21B
021/10 () |
Field of
Search: |
;175/231,232,234,243,296,297,107,317 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Neuder; William
Attorney, Agent or Firm: Killworth, Gottman, Hagan &
Schaeff, LLP
Parent Case Text
This application is a continuation of Ser. No. 08/844,446 filed
Apr. 18, 1997 abandoned.
Claims
I claim:
1. Apparatus for effecting pulsations in a flow of liquid
comprising:
an elongated hollow housing defining a primary flow passage adapted
to carry a flow of liquid axially therealong;
an elongated conduit having an upstream end and a downstream end
extending within said housing and defining a main flow passage
interiorly of said conduit which communicates at its downstream end
with said primary flow passage, and a by-pass flow passage
extending lengthwise of said conduit from said upstream end to said
downstream end thereof;
a nozzle located in said hollow housing adjacent to and spaced from
the upstream end of said conduit and adapted to discharge flow
passing along said primary passage into said main flow passage
defined by said conduit; the space between said nozzle and said
upstream end providing communication between said main flow passage
and said by-pass flow passage;
an axially movable valve member located in the downstream end of
said conduit and co-operating with a valve seat located downstream
of said valve member for interrupting the flow through said
conduit; there being one or more further passages downstream of
said valve seat providing communication between said main flow
passage and said by-pass passage in a region downstream of said
valve seat;
a spring for urging said valve member toward an open position in
the upstream direction; said valve member being adapted to move to
a closed position in response to flow along said valve member thus
interrupting the flow through said conduit and creating a water
hammer pulse which travels upstream through said conduit and said
nozzle and also through said space between said nozzle and the
upstream end of said conduit whereupon said pulse also travels
downstream along said by-pass passage and through said further
passage(s) to said region downstream of said valve member thus
tending to momentarily equalize water hammer pressures on upstream
and downstream sides of said valve member with said spring being
adapted to move said valve member away from said seat under these
equalized pressures whereupon flow within said conduit again
commences thus again effecting the closure of said valve member
whereupon the above recited sequence of events is repeated to
produce a cyclical water hammer and flow pulsating effect.
2. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 1 wherein said space between said nozzle and
said upstream end of said conduit is in the form of an annulus with
said nozzle and said upstream end together providing a jet-pump
effect and suction on liquid in said by-pass passage.
3. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 1 wherein said valve member is shaped such
that fluid flow therealong creates a Bernoulli effect and a
pressure loss between upstream and downstream portions of the valve
member thus tending to effect said momentary closure against forces
exerted by said spring.
4. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 2 wherein said valve member is shaped such
that fluid flow therealong creates a Bernoulli effect and a
pressure loss between upstream and downstream portions of the valve
member thus tending to effect said momentary closure against forces
exerted by said spring.
5. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 4 wherein said valve member is mounted for
axial reciprocation within a valve housing disposed in said
downstream end of said conduit, said spring being a coil tension
spring located in said valve housing and secured to said valve
member for urging same axially in the upstream direction.
6. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 2 wherein the time said valve member remains
closed during each cycle of operation is given approximately by the
formula
where:
L is total length in feet the pulse travels in upstream and
downstream directions in each cycle,
VC is speed of sound in drilling liquid (ft/sec)
T.sub.c is time valve stays closed per cycle (seconds).
7. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 5 wherein said valve housing and valve member
are located in an enlarged diameter downstream portion of said
conduit.
8. Apparatus for effecting pulsations in a flow of liquid in
accordance with claim 2 wherein said elongated housing is adapted
to be fitted into the lower end of a drill string and has threaded
connections at its opposing ends for connection between a drill bit
and a lower end of a drill string whereby in operation to produce
pulsations in a flow of drilling fluid passing through the drill
string to the drill bit.
9. A method for effecting pulsations in a flow of liquid
comprising:
causing a flow of liquid to travel axially along an elongated
hollow housing defining a primary flow passage;
providing an elongated conduit having an upstream end and a
downstream end extending within said housing and defining a main
flow passage interiorly of said conduit which communicates at its
downstream end with said primary flow passage, and a by-pass flow
passage extending lengthwise of said conduit from said upstream end
to said downstream end thereof;
discharging flow passing along said primary flow passage through a
nozzle located in said hollow housing adjacent to and spaced from
the upstream end of said conduit and into said main flow passage
defined by said conduit; the space between said nozzle and said
upstream end providing for communication between said main flow
passage and said by-pass flow passage;
interrupting the flow through said conduit by way of an axially
movable valve member located in the downstream end of said conduit
and co-operating with a valve seat located downstream of said valve
member; there being one or more further passages providing
communication between said main flow passage and said by-pass
passage in a region downstream of said valve seat;
effecting momentary stoppage of the flow within said conduit by
means of said valve member moving to a closed position in response
to flow and against the force of a spring for urging said valve
member toward an open position in the upstream direction thus
creating a water hammer pulse which travels upstream through said
conduit and said nozzle and also through said space between said
nozzle and the upstream end of said conduit whereupon said pulse
also travels downstream along said by-pass passage and through said
further passage(s) to said region downstream of said valve member
thus tending to momentarily equalize water hammer pressures on
upstream and downstream sides of said valve member thus permitting
said spring to move said valve member away from said seat whereupon
flow within said conduit again commences thus again effecting the
closure of said valve member whereupon the above recited sequence
of events is repeated to produce a cyclical water hammer and flow
pulsating effect.
10. A method for effecting pulsations in a flow of liquid in
accordance with claim 9 wherein said space between said nozzle and
said upstream end of said conduit is in the form of an annulus with
said nozzle and said upstream end together providing a jet-pump
effect and suction on liquid in said by-pass passage.
11. A method for effecting pulsations in a flow of liquid in
accordance with claim 9 including effecting said closure of the
flow by creating a Bernoulli effect and a pressure loss between
upstream and downstream portions of the valve member thus tending
to effect said closure of the flow against the forces exerted by
said spring.
12. A method for effecting pulsations in a flow of liquid in
accordance with claim 9 wherein the time said valve member remains
closed during each cycle of operation is given approximately by the
formula
where:
L is total length in feet the pulse travels in upstream and
downstream directions in each cycle,
VC is speed of sound in drilling liquid (ft/sec)
T.sub.c is time valve stays closed per cycle (seconds).
13. A method for effecting pulsations in a flow of liquid in
accordance with claim 9 wherein said elongated housing is fitted
into the lower end of a drill string between a drill bit and a
lower end of a drill string whereby in operation pulsations in a
flow of drilling fluid passing through the drill string to the
drill bit are provided.
Description
This invention relates to flow pulsing methods and apparatus for
use in various applications, such as in down-hole drilling
equipment and in particular to an improved flow pulsing method and
apparatus of this type adapted to be connected in a drill string
above a drill bit with a view to securing improvements in the
drilling process.
In the patent issued to Bruno H. Walter U.S. Pat. No. 4,819,745
issued Apr. 11, 1989 there is described in detail the classical
rotary drilling method and the manner in which drilling fluid or
drilling mud is pumped down ward through the hollow drill string
with the drilling mud cleaning the rolling cones of the drill bit
and removing or clearing away rock chips from the cutting surface
and then lifting and carrying such rock chips upwardly along the
well bore to the surface. That patent discusses the effect of jets
on the drill bit to provide high velocity fluid flows near the bit.
In general, these jets serve to increase the effectiveness of
drilling, i.e. they increase the penetration rate.
The above U.S. Patent also describes the use in the drill string of
vibrating devices thereby to cause the drill string to vibrate
longitudinally, which vibrations are transmitted through the drill
bit to the rock face thus increasing the drilling rate somewhat.
These prior art devices were subject to a number of problems as
noted in the above U.S. Pat. No. 4,819,745.
More recent forms of apparatus for increasing the drilling rate by
periodically interrupting the flow to produce pressure pulses
therein and a water-hammer effect which acts on the drill string to
increase the penetration rate of the bit are described in my U.S.
Pat. No. 4,830,122 issued May 16, 1989. These devices
(incorporating axially movable valve members) have provided a
significant improvement over the known prior art rotary valve
arrangements and have been less prone to jamming and seizing as the
result of foreign matter in the drilling fluid. At the same time
there was a requirement for higher pump operating pressures and
therefore these devices have not been able to be implemented on a
majority of drilling rigs.
A subsequent design of the flow pulsing apparatus described in my
U.S. Pat. No. 5,190,114 relies on the interruption of the flow by a
member operated by the reduction of the pressure due to the
Bernoulli Effect in the area under the movable member. This design
works very efficiently when the drilling fluid is water. However at
greater depth when the heavier drilling fluid is used, the
restricting member can stabilize and the effectiveness of the
system is reduced.
In all the above mentioned devices the restricting member would
start to open immediately following closure.
It has been learned since that it would be desirable to produce a
pressure pulse below the bit with a more pronounced negative phase
and a short delay between pulses. This characteristics can increase
the amount of cleaning action.
In view of the above it would be very desirable to provide flow
pulsing apparatus for the use in the drill string which would
operate reliably under any down hole conditions with heavy and
light drilling mud and at the same time provide a time delay
between negative and positive phase of the pressure pulse.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide improved
flow pulsing methods and apparatus for various applications wherein
vibrating and/or flow pulsing effects are desired, for example,
vibrating a drill string and a drill bit to increase the drilling
rate and to pulse the flow of drilling fluid emitting from the
drill bit jets thereby to enhance the cleaning effect and the
drilling rate. A further object of the invention is to provide
apparatus that would assure positive closure of the restricting
member regardless of the mud density and its subsequent opening. An
additional objective is to provide apparatus that would allow the
continuation of the drilling process without the benefit of the
pulsating flow, in the event that the restricting member fails in
operation and remains in the closed position.
Accordingly, the invention in one aspect provides a flow pulsing
apparatus including a housing providing a passage for a main flow
of fluid, and a bypass flow of fluid through a jet pump arrangement
that is at the top part of the main flow passage, and means for
periodically interrupting the flow through main passage to create
pulsations in the flow with a time delay between pulses and a
cyclical water-hammer effect to vibrate the drill string during
use. In particular, the main flow passage includes a valve that is
constantly urged upward by a spring or other means. Flow around
this valve is at such velocity that, due to the Bernoulli effect,
pressure is reduced between the valve and the valve seat. This
differential pressure acts on a projected area of the valve and the
valve is positively closed. The resulting water-hammer pressure
assures positive closure. Pressure below the suddenly closed valve
is reduced to the hydrostatic pressure while pressure above the
closed valve is at the water-hammer pressure. Immediately,
following the closure of the valve, energy in the fast flowing
fluid through the drill bit jets causes evacuation of a small
amount of drilling fluid from the area under the closed valve. This
effect reduces the pressure in the affected area below the
hydrostatic pressure (for a fraction of time) and cleaning action
on the bottom of the drilled hole is further enhanced.
The resulting force on the valve is much greater than the
continuous force that urges the valve constantly upward by a spring
or other means. Water-hammer pressure now travels upward at the
speed of sound in the particular fluid until it reaches the jet
pump arrangement. Once the water-hammer pressure increase reaches
the jet pump arrangement it continues upward through the main flow
passage and through the drill string section. At the same time
water hammer pressure increase travels at the speed of sound around
the main flow passage into the bypass flow passage downward until
it reaches the bottom part of the closed valve. Following a short
time delay, pressure under the closed valve and pressure above the
closed valve are at the same water-hammer pressure and the valve is
now urged upward by the compressed spring or other means. The cycle
is now repeated.
The invention also includes a flow pulsing method including the
basic actions noted above. The novel method allows for a time delay
between pulses and also a more pronounced negative pulse that
precedes the positive pulse for the purpose of better disturbing
bottom hole conditions and improving the hole cleaning.
In the preferred form of the invention the flow pulsing apparatus
is adapted to be connected in a drill string above a drill bit to
"pulse" the flow of drilling fluid passing toward the bit thereby
to vibrate the drill bit and enhance the hole bottom cleaning
effect, thus increasing the drilling rate.
In the embodiment to be described hereafter the control means takes
a form of a valve that is urged by a spring or by other means
upward from the valve seat and arrangement of the main flow passage
above the valve means to allow for the water-hammer pressure pulse
to exit through the jet pump arrangement into the bypass flow
passage and to continue down until it reaches under the valve means
to equalize the pressure above and under the valve.
The invention will be better understood from the following
description of preferred embodiments of same, reference being had
to the accompanying drawings.
BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS
FIG. 1 is a longitudinal section through an apparatus for producing
high frequency pulses in the drilling fluid in accordance with a
preferred embodiment of the invention;
FIG. 2 is an enlarged portion of the FIG. 1 showing the flow
pulsing means in further detail;
FIG. 3 is showing unrestricted flow pulsing means and the jet pump
arrangement situated above;
FIG. 4 is showing fully closed flow pulsing means and the jet pump
arrangement;
FIG. 5 is a cross-section view taken along line 5--5 of FIG. 1;
FIG. 6 is a cross-section view taken along line 6--6 of FIG. 1;
FIG. 7 is a cross-section view taken along line 7--7 of FIG. 1;
FIG. 8 is a cross-section view taken along line 8--8 of FIG. 1;
FIG. 9 shows a diagram of the pressure pulse in time above the
valve means;
FIG. 10 shows a diagram of the pressure pulse in time below the
valve means.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-8 a preferred embodiment of the invention is
shown in detail. The apparatus 20 includes an external tubular
housing (defining a primary flow passage) including upper housing
21 and lower housing 22. Upper housing 21 has an externally
threaded portion 23 for connection to the lower end of the drill
string (not shown), while lower housing 22 has an internally
threaded portion 24 for connection to a conventional drill bit 25
(shown in phantom) having conventional bit jets 26 for bottom hole
cleaning as noted previously.
The lower housing 22 is connected to the upper housing 21 via
tapered threaded portions 27.
In the upper portion of the upper housing 21 is located a velocity
increasing nozzle 28. Nozzle 28 is supported by a ledge 29 and a
seal arrangement by "O" rings 30 prevents leakage of the drilling
fluid around the cylindrical portion 31.
Accelerated flow of the drilling fluid exiting nozzle 28 enters a
jet pump arrangement 32 of the wash pipe 33. Main flow passage is
through the tapered entrance 80 and is defined by the Internal
Diameter 34. Flow than continues through the diffuser like passage
35 to a passage with the enlarged Internal Diameter 36.
Jet pump action of the accelerated flow exiting from the nozzle 28
and entering the upper portion 80 of the wash pipe 33 will create a
weak suction of the fluid from the area 37 surrounding the wash
pipe 33 and the valve housing 38.
Wash pipe 33 is kept in the center of the upper housing 21 by
welded ribs 39 which are more clearly shown on the FIG. 7. Wash
pipe 33 is kept in the center of the lower housing 22 by welded
ribs 40 which are more clearly shown on the FIG. 8. Welded ribs 40
are in contact with the Internal Diameter of the sleeve 41. This
sleeve 41 streamlines the bypass flow passage 37. Bottom portion of
the wash pipe 33 is inserted into the top opening of the valve
housing 38 and is resting on the shoulder 42. Seal between the main
flow passage and bypass flow passage is provided by "O" rings
43.
Valve housing 38 is inserted into a valve seat housing 39 at the
reduced diameter cylindrical portion 40 and is resting on the
shoulder 41. Seal between the main flow passage 44 and bypass flow
passage 37 is maintained by "O" rings 45. In the valve seat housing
39 is inserted valve assembly 46, base ring 48 and heat shrink
fitted a tungsten carbide valve seat 47. Valve assembly is more
clearly shown on FIG. 2. and FIG. 5 where cross-section through the
line 5--5 is shown.
On FIG. 2 valve assembly 46 consist of a "spider" 49 which has a
cylindrical portion 50 that is inserted into the valve seat housing
39. "Spider" 49 has flow passages 51 shown on FIG. 5 and FIG. 2 and
in its center a hollow cylindrical portion 52 that surrounds by a
heat shrink fit a tungsten carbide valve bearing 53 on the bottom
end and on the opposite top end a reduced size pipe like portion
54. On the outside of the portion 54 is a tapered threaded
connection 55 with which a spring housing 56 is connected. Through
the top portion of the "spider" 49 protrudes a valve puller 57.
Around the valve puller 57 is located pre stressed compression
spring 58. Spring 58 rests on the top part of "spider" 49 and its
top end is continually in contact against face 59 of the epoxy
glued nut 60.
Bottom end of the valve puller 57 is an enlarged hollow cylindrical
portion 61 which surrounds by heat shrink fit a top end of the
tungsten carbide valve 62. This valve 62 is urged upward by a
spring 58 and when it is in its most upward position it is
prevented from further movement by a shoulder 63.
Main drilling fluid flow through the area 66 that is between the
bottom conical surface 64 and the top conical surface of the valve
seat 47 is at high velocity. Bernoulli effect reduces the pressure
in this fast flow and at the same time creates a pressure loss
between area above the valve 62 and below the valve. This
differential pressure acting on the projected area of the valve
creates a force stronger than the resistant spring force and valve
moves down until bottom portion of the valve 64 sets firmly onto
top portion of the valve seat 65. Venting of the area 67 is
provided by a venting hole 68. Venting of the area 69 is provided
by a venting hole 70.
Valve seat 47 is heat shrunk into a valve seat housing 39. Valve
seat 47 is resting on top of the base ring 48 cylindrical portion
71.
Base ring 48 is shown in cross-section along line 6--6 shown on
FIG. 1 where are shown holes 72 which allow communication between
the bypass flow passage and bottom end of the main passage 73.
In operation of the embodiment shown in FIGS. 1-8 the drilling
fluid or mud is being pumped downwardly as shown by arrow 74. Flow
is accelerated in the nozzle 28 and it continues into the bore of
the wash pipe 33. Top portion of the wash pipe 33 is separated a
short distance from the bottom end of the nozzle 28 and is produced
to resemble a jet pump configuration. This area therefore functions
as a jet pump and assures flow through the main flow passage 44 as
long as the valve 62 is in its open position as shown on FIG. 3.
Action of the jet pump arrangement causes a small flow from the
bypass flow passage 37 into the main flow passage 44.
Flow of the drilling fluid continues downwardly and around the
valve assembly 46. Flow between the bottom surface 64 of the valve
62 and the top surface 65 of the valve seat 47 is maintained at the
high velocity and due to Bernoulli effect pressure in this area is
reduced. At the same time after flow passes through this area 66 it
experiences a pressure loss.
Valve 62 which is continually urged upward by a spring 58 is now
subjected to the differential pressure above the valve 62 and below
the valve 62. This differential pressure now acts on the projected
area of the valve 62 and resulting force which if far greater then
the upward force delivered by spring 58 now causes downward
movement of the valve 62 until it reaches a fully closed position
as shown on FIG. 4.
When the valve 62 reaches the closed position a water hammer
results and all kinetic energy of the flowing drilling fluid
directly above the closed valve is converted into pressure rise.
This water-hammer pressure now travels upward at the speed of sound
in the particular fluid. Below the closed valve 62 pressure is
instantly reduced to the hydrostatic pressure and if the small
diameter drill bit nozzles are used inertia of the fast flowing
fluid through the drill bit nozzles will evacuate some fluid out of
the main flow passage 73 resulting in a negative pressure that
would be lower than hydrostatic pressure.
When the water-hammer pressure reaches the top portion of the wash
pipe 33 it will now continue into the bypass flow area 37 and
continue downward until it exits through the holes 72 and under the
closed valve 62 and into the bottom part of the main flow passage
73. At the same time water-hammer pressure will also travel upward
and into the bore of the drill string that is connected by a
threaded connection 23 on the top of the housing 21.
It should be noted that length "L" as shown on FIG. 3 and FIG. 4
will determine the total time during which a flow of the drilling
fluid is interrupted and the conditions for the water hammer
pressure above the closed valve 62 and reduced pressure under the
closed valve 62 are present.
Total time during which the valve 62 is kept closed by water hammer
pressure is governed by the time that this water-hammer pressure
takes to travel to the top of the wash pipe 33 and then through the
bypass area down and through the holes 72 and under the closed
valve 62, at which point the pressure is equalized under and above
the valve 62 thus allowing spring 58 to lift valve 62 to its open
position as shown on FIGS. 1-3. This time can be calculated
approximately by formula
where
"L" is length in feet
vc is velocity of sound in ft/sec
Tc is time during which the valve is closed.
Characteristic of the water hammer pressure pulse above the valve
are shown on FIG. 9 while characteristics of the water-hammer
pressure pulse below the valve are shown on FIG. 10.
If, during the operation of the valve assembly 46 the spring 58
breaks and the valve 62 remains continually in the closed position
flow can be established automatically through the area between the
top portion of the wash pipe 33 and into the bypass area 37
downwardly through the holes 72 into the bottom part of the main
flow passage 73 and through the drill bit nozzles 26. This feature
would allow for a continuous drilling operation without the
requirement to pull up the drill string. Active cross-section of
the bypass flow is made larger than the main flow area resulting in
the requirement for a somewhat lower pressure required to pump
through the disabled apparatus. This lower pressure would be
registered on the surface and drilling personnel would know that
tool is disabled.
Other suggested uses of the invention in the course of the
down-hole operations are:
a) shaking of tubing to clean screens;
b) vibrating of cement during cementing operations;
c) pulsating a fluid being pumped into a formation to fracture
it;
d) vibrating a fishing jar to free a stuck drill string.
Numerous non-drilling related applications wherein pulsation in a
flow of fluid are desired will become apparent to persons skilled
in the art of fluid mechanics generally.
Many variations of the flow pulsing apparatus will become apparent
to those skilled in the art from the description given above. For
definition of the invention reference should be had to the appended
claims.
* * * * *